Recent publications have described the use of short time high temperature annealing to minimize dopant diffusion during post implantation annealing. The silicon is heated by radiation from light sources including tungsten-halogen lamp arrays, argon discharge lamps, xenon flash lamps and resistance heated black bodies. These high temperature radiation sources have the capability of rapidly heating silicon to a temperature of 1000.degree.-1200.degree. C. for controlled short periods of time.
In the E.sup.2 PROM's a thin oxide is grown over a portion of the drain, after which a heavily doped polysilicon floating gate is fabricated. FIG. 2 shows a portion of a typical device including the body 11 with drain 12. An oxide layer 13 including a thin region 14 at the drain is formed on the surface of the device. A floating gate 16 is formed on the oxide layer 13. The device then includes another oxide layer 17 and an external gate 18. In operation, a high electric field is established between the floating gate and the drain, permitting electrons to tunnel from the drain to the floating gate, or vice versa. The charge supplied to the floating gate modifies the threshold voltage of the device in normal operation, thus permitting its use as a memory element.
The thin oxide is presently fabricated by conventional oxide grown at relatively low temperatures (800.degree. C.) in order to limit the growth to approximately 100 .ANG.. However, the "pin hole" density in the oxide, electric field at breakdown and charge trapping density characteristics of the oxide grown at this low temperature are not optimal for the device. Dense oxide layers are also important in VLSI devices. The characteristics of oxide layers are improved by increasing the oxidation temperature to 1100.degree. C.; however, the oxide growth rate at 1100.degree. C. is so large that conventional oxidation techniques cannot produce oxides with a well controlled thickness in the 100 .ANG. range needed for E.sup.2 PROM's, VLSI devices, MOSFETS and other semiconductor devices.